Method and means for effecting automatic fractionation



Oct. 26, 1954 c. p. 'ALWAY ET A1. 2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28,1950 10 Sheets-Sheet 1L IISV-AC RECTIFIER t FILTER UNIT A I59 I CLAYTOND. ALWAY I NORMAN DRAKE WILL/AM a. HA/NES 1 OL/v R R. Wooos 9- t by M 3mentors attorney Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOREFFECTING AUTOMATIC FRACTIONATION 1O Sheets-Sheet 2 Filed 001;. 28, 1950CLAYTON D. AL WAY NORMAN A. DRAKE lnventors W/LL/AM L/ HA/NES OLIVER RWooos 8g i/ /morneg Oct. 26, 1954 c. D. ALWAY ETAL METHOD AND MEANS FOREFFECTING AUTOMATIC FRACTIONATION l0 Sheets-Sheet 3 Filed Oct. 28, 1950Zinnentors Y 4 E 3/ M M m M 2 bH 3 AJ NN 0AM TM/ V: L M CNW mw (IttomegOL/l/EA WOODS Get. 26, 1954 c. D. ALWAY ET AL 2,692,820

METHOD AND MEANS EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 195010 SheetsSheet 4.

CLAYTON D4 AL WA Y NORMAN A. DRAKE 7 W/LL/AM H 5 Imventors OLIVER R.I/VOODS Cttomeg Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOREFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28, 1950 10 Sheets-Sheet 5r CLAYTON D. AL WAY NORMAN A DRAKE WILL/AM J. HA/NES 3nveutors OLIVE/P RWo'oos Oct. 26; 1954 Filed Oct. 28, 1950 'lmlllll lllll c. D. ALWAY ETAL ,69 METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION 1OSheets-Sheet 6 -IGB CLAYTON D. ALWAY NORMAN A, DRAKE WILLIAM J. HA/NEsOLIVER R. I/I/ooos Zmvenlors Oct, 26, 1954 c, D ALWAY ET AL 2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28,1950 10 Sheeis-Sheei 7 CLAYTON D. ALWAY NORMAN A. DRAKE OL/ vER R. Woo0sWILLIAM J HA/NES Zmvenms 1954 c. D. ALWAY ET AL ,6 2,82@

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION I 1O Sheets-Sheet8 Oct. 26,

Filed Oct. 28. 1950 Oct. 26, 1954 c. D. ALWAY ET AL METHOD AND MEANS FOREFFECTING AUTOMATIC FRACTIONATION 10 Sheeis-Sheet 9 Filed Oct. 28, 1950WAY NORMAN A DRAKE 3nventors CLAYTON D. AL

WILLIAM 0, HAINES OLIVER R Woooa Get. 26, 1954 C. D. ALWAY ET AL2,692,820

METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Filed Oct. 28,1950 10 Sheets-Sheet 10 CONTROL H5v AC fig. 20

501. velvr SELECTOR curruw;

POINT CONTROL CoMPA RATOI? COUN TEE AMPL/ FIE E PELA AMPL/F/ER CLUTCHCONTROL LAMP CHANGE CLAYTON D. ALIA/Av NORMAN A. DRAKE 5 TARTER VOLTAGEOLIVER R" WOODS attorney WILLIAM J H 5 ISnventors Patented Oct. 26, 1954METHOD AND MEANS FOR EFFECTING AUTOMATIC FRACTIONATION Clayton D. Alwayand William J. Haines, Kalamazoo, Oliver R.

Woods, Scotts, and Norman A. Drake, Kalamazoo, Mich., assignors to TheUpjohn Company, Kalamazoo, Mich, a corporation of Michigan ApplicationOctober 28, 1950, Serial No. 192,722

17 Claims.

stantially manually. Thus, the continuous presif ence of a skilledoperator for changing the receptacles in which the product is collected,for changing the solvent being introduced into the column, and forfilling the proper number of receptacles with any given solvent and/orsolute as products of the fractionation has been necessary where suchprocesses have formerly been desired. However, due to the slow action ofa fractionating column, an operation involving same often extends over aperiod of several days during much of which time the operator isfrequently idle. Furthermore, unless shifts of operators are providedbeyond the normal working hours, the process must be stopped overnightwhich often introduces further complications.

Accordingly, it becomes apparent that the provision of an entirelyautomatic instrument which can be pre-set by an operator to effect theabove mentioned operation and then be disregarded, would not onlyrelieve the operator for other work, but would also permit continuousoperation of the process over extended periods of time. By the equipmenthereinafter disclosed, collection of a series of fractions, which wouldrequire days by ordinary procedures, may now be accomplished in a fewhours.

Accordingly, a primary object of this invention is the provision of aninstrument for automatically separating and collecting the respectivecompounds eluted from a fractionating column.

A further object of this invention is the provision of an instrument, asaforesaid, having means for supporting a plurality of containers forcollecting eluted compounds and further means for automaticallypositioning said containers during the collection of said elutedcompounds.

A further object of this invention is the provision of an instrument, asaforesaid, having means for automatically controlling the amount ofeluted compounds collected by said individual containers.

A further object of this invention is the provision of an instrument, asaforesaid, having means for introducing in a predetermined sequence avariety of solvents into a fractionating column.

A further object of this invention is the pro vision of an instrument,as aforesaid, having means for controlling the period during which anyparticular solvent is directed into said fractionating column and,accordingly, the number of containers which are filled with dischargefrom the column including a particular solvent.

A further object of this invention is the provision of an instrument, asaforesaid, having means insuring a continuous supply of a given solventto the fractionating column.

A further object of this invention is the provision of an instrument, asaforesaid, which can be operated over a relatively long period of timewithout constant attention from an operator.

A further object of this invention is the provision of an instrument, asaforesaid, which greatly reduces and greatly simplifies the separationand collection in fractions of compounds eluted from a fractionatingcolumn, over methods and means presently available.

Other objects and purposes of this invention will become apparent topersons familiar with this type of operation upon referring to theaccompanying drawings and upon reading the following specification.

For illustrations of a preferred embodiment of our invention, attentionis directed to the accompanying drawings in which:

Figure 1 is a broken side elevation view of an automatic instrument fordetecting, separating and collecting in fractions compounds eluted. froma column, including schematically a portion of the electric circuitryinvolved.

Figure 2 is a sectional view substantially as taken along the line IIIIof Figure 1.

Figure 3 is a sectional view substantially taken along the line III-IIIof Figure 2.

Figure 4 is a sectional view substantially taken along the line IVIV ofFigure 3.

Figure 5 is a sectional view substantially taken along the line VV ofFigure 2.

Figure 6 is a sectional view substantially taken along the line VI-VI ofFigure 5.

Figure 7 is a sectional view substantially taken along the line VII-VIIof Figure 5.

Figure 8 is a sectional view substantially taken along the lineVIII-VIII of Figure 5.

Figure 9 is a sectional view substantially as taken along the line IX-IXof Figure 6, and for convenience in showing is rotated approximately 90degrees in a counterclockwise direction.

Figure is a sectional View taken along the line X-X of Figure 9.

Figure 11 is a sectional view as taken along the line XIXI ofi'F-igure10;

Figure 12 is a sectional view taken substan tially along the lineXII-XII of Figure 1.

Figure 13 is a fragmentary view of a tape and means associated therewithforrecordingmermanently and visually the operation of? the instrument towhich this invention relates.

Figure 14 is a sectional view substantially as taken along the lineXIV-XIV of Figure. 1.

Figure 15 illustrates diagrammatically a. circuit energizing the fillcontrol lamp.

Figure 16 illustrates diagrammatically the electric circuit responsiveto thefilling ofan individual container for effecting moving ofv thenext:

successive container into: filling position.

Figure 17 shows diagrammatically a. circuit, adapted for use to.distinguish the differential between the radiation'passing through thesample being tested and through a standard.

Figure 18 represents the counter circuit to gether with the meansdirectly 'connectedthereto.

Figure" 19 represents a suitable power supply circuit.

Figure 20' represents a schematic diagram of the entiremechani'smshowing primarily the relationship between the variousportions of the electrical circuit together with their functionalassociation with the mechanical parts.

Figure 21 illustrates therecorderconnections.

GENERAL DESCRIPTION In meeting those objects and purposes here.-

tofore mentioned, as, Well as others incidental.

tionating column and the container being filled.

at a given moment. The difierentiating head is provided with means fordetermining when the concentration of. eluted material being separatedfrom the fractionating column by a particular solvent rises to, or dropsbelow, a predetermined value. The differentiating head then initiatesaction to change the solvent. and posi tions another container forcollection of further. solvents and eluted compounds dissolved therein.The difierentiating; head in the; specific embodiment here chosen forillustrative purposes comprises a source of electromagnetic radiation ofa wavelength absorbable in the compound desired and means responsive tothe differential in absorption ofsuch radiation passing (1) throughone'transparent cell containing the solvent andv the said compound and(2) through another transparent cell containing only solvent.

However, it will be appreciated as the detailed description progressesthat the apparatus and method may also-utilize other types of.radiation.

energy as light of other wavelengths or an electron beam, and. othercharacteristics than absorptiveness. of the material being sought as itspower of optical or magnetic rotation or index of refraction, and theseitems will be selected according to the characteristics of the materialbeing separated.

An electrical system which effects and controls the operation of theseveral parts, comprises first, a counting device by which the solventcontrol valves are changed when a predetermined num ber of containershave been filled with the products of the fractionating column, andsecondly, means responsive to control of the differentiating'; head" to.block operation of the counting device so long as said products maintaincertain preselected: absorption characteristics. A recorder is' also.provided independently of the valve changingmeans for indicating andrecording the amount. of said. eluted material in the column eflluent atany given time. The recording means ishere" shown as visual, but itcould also he audible.

Means are also herein provided for urging the solvents from. theirrespective receptacles. into a. ool'lectingchamher attached to the inletend of the. fractionating column;. and for maintaining a constantsolvent level' in said chamben.

For the purpose of convenience in the detailed description whichfollows; the terms upper and" lowerj? as used herein will be understoodto refer to the instrument It when in its normal operating position; asappearing in" Figure 1. The terms inner or inwardly? and outer oroutwardly shall have reference-to the geometric center of the instrumentit) or" parts thereof.

The method and device here disclosedmay be usedfor either'partitionchromotography or the adsorption chromotography, or for other methods ofsolvent extraction wherein determination-of the amount of" eluted'material present at a given time in the" discharge from the column maybe desiredi CONSTRUCTION Turntable and mechanical portion of itsactuatz'ng means upon. and. secured. torthe base plate i l whereby said:turntable: is free to rotate in? a horizontal plane. The purposezof. theturntable H and parts associated therewith. is to move the containersit. supported" thereon successively into position for reception, one ata time, ofv liquid. released. from a fractionat-ingcolumn through adifferentiating head it.

Althougha: circular. turntable i I is specifically shown, forillustrative purposes only, the means supporting the containers t2. tobe filled with the solution flowing from the fractionating column, itwill be readily realized that other conventional, conveyor means, suchas a straight line. conveyor, may be used alternatively within the scopeof. this. invention.

The turntable H is comprised of a circular topplate or disk ll.(Figures 1. and 2) having anl5 and passing openings 2| being equidistantfrom the axis thereof. The openings 2! are preferably circular andidentical in diameter.

The peripheral edge 22 of the disk I1 is provided with a plurality ofequally spaced cams or projections 23 lying within the plane of the diskand extending radially and equidistantly therefrom. The projections 23are equal in number to the number of openings ER in the disk H and arepreferably, but not necessarily,

aligned with said openings along respective radii of the disk.

A micro-switch F2, having a roller contact 73, is supported, ashereinafter described, adjacent to the turntable II so that said contact13 is in continuous engagement with the peripheral edge 22 of the diskH. The switch 12 is arranged so that it will be normally closed when theroller contact 13 is engaging the edge 22 between any pair ofprojections 23, and normally open when said contact is engaged by aprojection 23.

The turntable H is also provided with intermediate and lower containersupport rings 24 and 25 respectively, which are spaced downwardly from,and suspended upon, the disk ll by means of the connecting rods 26. Theintermediate and lower rings preferably have outside circumferencessubstantially equal to the cirumference of the disk I! and are coaxialwith the pivot post 13. The intermediate ring 24 is provided with aplurality of container openings 2? therethrough, which openings aresubstantially equivalent in size, radial disposition, and verticalalignment with the container openings 2! in the plate I? (Figure 5).Thus, containers l2, such as test tubes, inserted through the containertopenings 2! will also extend through the container openings 2?.

The lower ring 25 is provided with suiiicient horizontal surface and isso disposed to engage and support the lower ends of the containers l2when they are positioned within the openings 2i and 21. Convenientmeans, such as the rubber bumpers 28 (Figure 5), may be inserted throughappropriate openings of the lower ring 25 for the purpose of cushioningthe support of the container l2.

A circular gear 29 (Figures 2, 4 and 5) is secured to the bottom of, andis coaxial with, the support sleeve 18 upon which the disk I"? ismounted. Thus, rotation of the gear 29 effects a rotation of the disk ifand the rings 24 and 25 suspended therefrom. The gear 29 is engageablewith and rotatable by the worm gear 3i secured upon a horizontal shaft32 (Figures 2, 3 and 4). The shaft 32 is rotatably supported adjacent toone end thereof upon the vertical end plate 33, which is in turnsupported upon the base plate l4 in any convenient, conventional manner.The other end of the shaft 32 is rotatably held in a bearing support 3 5which is mounted upon a horizontal support plate 35 (Figures 1, 2, 3 and4) mounted between and upon said end plate 33, another end plate 36 andthe pivot post I3. An electric motor 3?, or similar means, is securedupon the base plate l6 beneath the support plate 35 so that its shaft 38is preferably parallel with and directly below the shaft 32, andextending toward the end plate 33, A stub shaft 39, which is coaxialwith; extends toward, and is spaced slightly from, the motor shaft 33,is rotatably supported by means of the bearings 4| mounted within theend plate 33. Both the worm shaft 32 and the stub shaft 39 extend 6through and beyond the outer side of the end plate 33 for engagement by,and support of, a pair of pulleys 42 and 43, respectively, which aremutually engaged by a chain 44 or similar drive means (Figures 1 and 3).

A clutch 45 (Figures 1, 3 and 5) is mounted upon the motor shaft 33 andthe stub shaft 39 between the motor 31 and the end plate 33 to effectintermittent, controlled rotation of the Worm gear 3|.

In this particular embodiment, the clutch 45 (Figures 3 and 4) iscomprised of one circular clutch plate 46 mounted upon and rotatablewith the motor shaft 38, and another circular clutch 7 plate 4'! ismounted upon the inner side of the end plate 33 around the stub shaft39. The clutch plates 46 and 4'! are provided with circular clutch bands48 and 49, respectively, on their opposite faces. A circular clutchmember 58, having a pair of parallel faces 5! and 52, is secured uponthe stub shaft 39 between the clutch plates 46 and 47 for axial movementbetween the clutch plates 46 and 47. The faces 5| and 52 are engageablewith the clutch bands 48 and 49, respectively. Thus, upon appropriateaxial movement of the clutch member 50 toward the clutch plate 36, theclutch face 5| will engage the clutch band 48 in a conventional mannerand rotation of the motor shaft 38 will thereby effect rotation of thestub shaft 39. Movement of the clutch element 50 toward the clutch plateM, will cause engagement between the clutch face 52 and the clutch band49, thereby causing the clutch member 56, if rotating, to stop quickly,also in a conventional manner.

The clutch member 56 (Figure 3) is provided with a relatively deep,annular groove 53 between its two parallel faces 5| and 52. A sleeve 5;encircles the clutch member 59 within the annular groove 53, thereof,and is rotatably mounted upon the clutch member 50 by means of a bearing55. A yoke 56 (Figures 3 and 4) extends about the sleeve 54 and its armsare pivotally secured to the sleeve 54 by means of the pins 51. The armsof said yoke 55 are rotatably supported at their free ends upon asubstantially vertical rod 58 extending therethrough and secured at itsopposite ends to the base plate 24 and the support plate 35.Accordingly, movement of the yoke 56 in a horizontal plane will effectaxial movement of the clutch member 59 back and forth between the clutchplates 46 and 4?.

A horizontal bar 59 (Figures 1 and 4) is secured to the yoke 56 andextends therefrom for pivotal engagement at its opposite end by theactuating arm El of the solenoid 62 mounted on the base plate M.

A resilient means, such as the spring 63, is connected at one end to thebar 59, adjacent to the actuating arm 6!, and is anchored at its otherend upon a post 64 mounted upon the base plate H4. The spring 63, beingunder tension tends to urge the bar 59 away from the solenoid 52 wherebythe yoke 56, acting through the pins 57, urges the face 52 of the clutchmember 59 against the clutch band 49 on the clutch plate 4?, therebypreventing rotation of the clutch member 56. Actuation of the solenoidEL urges the bar 58 toward the solenoid, thereby causing the face it ofthe clutch member 5!! to engage the clutch band 48 on the clutch plate46, whereupon the motor 3'! may effect a rotation of the stub shaft 39.

During normal operation of the instrument ,manner to a source of power.

aeoagseo:

I; the-motor 31 is in continuous operation and of the solenoid 62- bythe micro-switch 12* or by:

other means hereinafter described.

DIFFERENTIATING HEAD The differentiating head l6. (Figures 1, 2 and.

) is supported upon a horizontal cross bar H which issecured tothe topsof a pair of parallel support bars 70 and Ella which are in turnmountedupon the base plate I l adjacent to the turn table II, so thatsaid. head IB- extends over the top-disk. llv of the turntable H. Thehorizontal cross bar ll extends laterally beyond the support bar 'lflandadjacent to the peripheral edge 22-0f. the topdisk IT for the-support ofthe microswitch 12 in the manner described hereinabove.

The differentiating head i6, is divided into inner, intermediate andouter compartments i4, 15 and 16, respectively, by reference to thepivotpost I3 of the turntable H, with appropriate,

inner and outer partitions 11 and- 18 between the compartments M. and 15and the compartments l5 and 16, respectively.

A- source of radiant ener y, such as an ultraviolet tube 19 (Figures 5andv 6), is centrally disposed. within the inner compartment Hi and iselectrically connected in any conventional As mentioned above, the typeof. radiation may vary within the scope of this invention and may be anytype or Wavelength which will be absorbed, or otherwise physicallyaffected, by the compounds being collected. While it is preferred thatsuch absorption be in a substantially lineal relationship to theconcentration of said compounds in the eluted solution, otherrelationships may be usedv where less accuracy is required or uponproper compensation of the electrical circuit responsive to suchabsorption. However, in this particular embodiment for extractingsteroids containing aconjugated diene system, e. g., cortical steroids,ultra-violet light having a wavelength, of 2,537 Angstrom units has beenfound advantageous. A baflle plate 8| is supported from the top82 of thedifferentiating head It for preventing said ultra-violet radiation ofthe tube 19 from escaping through a vent opening 83. in the top 82. Alight opening 84 is provided in the partition. ll adjacent to the tube19 through which the radiation emanating therefrom may pass into theintermediate compartment 15.

A filter 85 (Figures 5 and 6) is disposed within the intermediatecompartment 15 adjacent to the light opening 84 in the partition H forthe purpose of controlling the wavelength of the radiation passing intothe intermediate compartment 15. However, where the rotary power of theeluted material is being utilized, this filter may be replaced by anysuitable means, as a Nicol prism, for polarizing the light from source I8' into a selected plane.

A pair of absorption cells 86 and 81, which are preferably mirror imagesof each other (Figures 5, 6, 9, 10, 11 and 14), are disposed within theintermediate compartment 15 adjacent to each other and so that radiationemanating from the tube '19 and passing through the light opening 8:3will be intercepted by both of said cells. Inasmuch as the cells 86 and87 are in this embodiment substantially identical, only the cell 85,through which the solvent and compounds dissolved therein pass, will bedescribed with the understanding that such de- 8:1 scription applies insubstance to the cell" 81 through which the solvent only passes.

As shown in Figures 6, 9, 10 and, 1.1, the absorption cell 86 iscomprised of a, block shaped body member 88, having a substantiallycylindrical light passage 89- passing horizontally therethrough. Thelight passage 89 is provided with cylindrical portions of enlargeddiameter at the opposite ends thereof which are internally threaded forreception of a pair of, externally threaded light gathering elements 91and: 92'.

Filters 93 are disposed in the passage 89" (Figure 11) between theelements 9! and 92" and the body member 88 so that they provide anabsorption chamber 94 within the bodymember 8 8.

A fluid inlet canal 85, which opens through the upper surface (Figure 9)of the bodymember 88, extends through said body member and communicatesWith the absorption chamber 94' near the bottom thereof. A fluid outletcanal 95, which opens through the bottom surface of the body member 88,communicates with the absorption chamber fi l near the top thereof,.. Avent canal 9i communicates between the top" surface of the body member88- and' the outlet canal 96. The inlet canal 95, where it opens throughthe top of the body member 88, is provided with an enlarged portionproperly beveledfor reception of a transfer tube 98' (Figures 9 and 14')from the fractionating column l5. The transfer tube 98 may be held insnug contact. with the walls of the opening of the inlet canal 95 by anyconvenient means, such as the clamping device 99 (Figures 6 and 9)secured tothe body member 88. Accordingly, solvent and any materialsdissolved therein flowing from the fractionating column [5 through thetransfer tube- 98 enter the bottom on the absorption chamber 9 8 throughthe inlet canal 95 and are carried off therefrom through the outletcanal 96. Therefore, in addition to the fact that the absorption cell 86must be positioned to permit light from the tube 19 to pass through thelight gathering elements 9i and 92 and the absorption chamber 9ithereof, said cells must also be disposed so that the lower end Hit ofthe outlet canal 95 is disposed directly over the center of the path ofthe containers 52 mounted on theturntable H. The axes of the lightpassages 89 through the cells 86 and 8! are disposed at anangle whichconverges at a point substantially at the center of the tube i9, wherebyradiation from' the tube l9 will pass through the absorption chamber 915of both cells.

The outer partition 18 is provided with a pair of spaced, light openingsH32 and H33 (Figures 5, 6 and '7), which are intercepted; respectively,

by said axes of the light passages through the absorption cells 86 and8'2; Thus, radiation from the tube 19 passes through the light opening86', the filter 85, the absorption chambers 941 of the absorption cells86' and 81; and the light openings Hi2 and I03, respectively, in theouter partition 78. A pair of cellssensitive to the radiant energy beamfrom the source 19, as photo-electric tubes Hi l and H15, are disposedwithin the outer compartment '56 of the differentiating head H5 so thatsaid radiation passing through the light openings Hi2 and lll3:willstrike the filaments of the photo-electric tubes IM and 15,respectively.

Where, the rotatory power of the material is being utilized, suitabledevices, such as a pair of Nicol prisms, may be inserted. in theretain:- ing devices H t and H2 (Figure 6) in place of 11 ceptacle MI isnot essential but has been found convenient. 7,

Each receptacle I4I (Figure 1) is provided with a hollow stopper I44through which an outlet pipe I45 extends downwardly adjacent to, butspaced slightly from, the bottom of the receptacle MI. The outlet pipeI45 communicates directly with the manifold chamber I32 (Figure 1) nearthe upper end thereof. An inlet pipe I46 communicates with the chamberin the hollow stopper I44, which chamber communicates in turn with theinside of the receptacle MI. The purpose of this arrangement is to forcea gas through the inlet pipe I46 into the receptacle I lI, whereby thesolvent within said receptacle is urged up through the outlet pipe I65and into the manifold chamber I32.

A by-pass pipe I41 (Figure 1) communicates between the upper end of themanifold chamber I32 and the upper end of the solvent control chamberI3I (Figure 12).

A gas under pressure, from means not shown, is fed into the by-pass pipeI41 through the supply pipe !48. A pressure regulating valve I49 isprovided in the supply pipe I48.

Each receptacle MI is provided with a pair of electrically actuated,regulating valves II and I52 (Figures '1 and with a connecting pipe I53therebetween. The inlet pipe I46, which communicates with the hollowchamber in the stopper hi l, also communicates with the connecting pipeI53. A pressure pipe I54 communicates between the regulating valve I5Iand the junction of the supply pipe Hill with the by-pass pipe I41.Thus, the gas flowing through the pipe I48 at a pressure regulated bythe valve I ls, flows into the solvent control chamber I3-I, themanifold chamber I32 and the regulating valve I5I. An auxiliary supplypipe I55 connected to the auxiliary supply of gas under pressure, notshown, communicates with the regulator valve I52.

The range of the pressure regulating valve M9 is preferably variablefrom zero to ten psi. The pressure of the gas supplied through theauxiliary supply pipe I55 is preferably approximately two p. s. i. inexcess of the pressure of the gas in the supply pipe I55. The regulatorvalves I5I and I52 are arranged so that one will be closed when theother is open. Thus, when the valve I5I is closed, as shown in Figure 1,the

pressure in the inlet pipe I56 will be about two p. s. i. in excess ofthe pressure in the outlet pipe I45, thereby causing the said solventtoflow under pressure through the outlet pipe I and into the manifoldchamber I32. When the positions of the regulator valves I5I and I52 areelectrically reversed, the auxiliary gas pressure is shut-off and thepressure in the pipes I45 and I46 will become equal, permitting gravityto draw the liquid in the outlet pipe I45 back into the receptacle MI.The electric circuitry involved in reversing the regulator valves I5Iand I52 upon energization of the energizing filter I39, will be dealtwith in detail hereinafter.

Briefly, each pair of regulator valves I5I and I52 (Figure 20) isprovided with a solenoid I58 (Figure 1) which is energized upon closingof the circuit thereof by the rectifier solenoid I56. Energization ofthe valve solenoid I58 (Figure 1) effects an electrical closing of thevalve I5I and opening of valve I52, which causes solvent to flow fromthe receptacle I4I into the manifold I32. When this circuit includingsolenoid I58 is opened by de-energization of the solenoid 12 I56, thevalve I52 is electrically closed and valve 'I5I is electrically opened.The solenoids I580; through I58d (Figure l) are provided for use withadditional pairs of regulating valves (Figure 20) which operate inidentically the same man her with appropriate solvent receptacles. Theplug I59 is connected to a suitable electrical device, discussedhereinafter, for closing the circuit containing that one of thesolenoids I56 through I 58d controlling the fiow of the desired solventaccording to a predetermined pattern.

RECORDER Referring to Figure 13, it will be seen that the instrument Itis provided with recorder I63 comprising a pair of pens I64 and I65 anda recording tape I66 upon which a visual record is made of thepercentage of absorption or transmission of ultra-violet radiation fromthe tube ls by the solvent and compounds dissolved therein passingthrough the absorption cell 85. The radiation from the tube I9 is ofsuch wave-length that it will be absorbed by the compounds dissolved inthe solvent. Thus, the amount of radiation passing through the cell 55is visually compared to the amount of radiation from the tube "I5passing through the absorption cell 8?, through which cell the plainsolvent is passing.

A minimum condition of absorption represented by the dotted line I61, isestablished below which the amount of compound in the solvent beingcollected by the containers and indicated by said absorption becomes toosmall for useful purposes. Obviously, this minimum can vary as ;desiredor required. The indices I58 along the curve I69 (Figure 13) made by thepen I64 represent points at which the filling of a new container I2commences. It will be noted that such indices always point toward theline I67 and, therefore, extend leftwardly of the curve I69 when thecurve is on the rightward side of the line I67, and extend rightwardlywhen the curve I69 is on the leftward side of the line I51. When theindices are pointing leftwardly, the containers are being filled withuseful compounds. When the indices are pointing rightwardly, apredetermined number of containers are bein filled with non-usefulliquid. If the pen I64 does not move to the right side of the line I61by the time this number of bottles is filled, the solvent isautomatically changed. The instrument III can be set by electricalmeans, hereinafter described in detail, so that a specific, preselectednumber of containers I2 will be filled with any particular solvent afterthe amount of compounds dissolved in the solvent and being collected inthe containers drops below the minimum line I61. In general, thispreselected delay in changing solvents insures satisfactory dissolvingof the materials in the fraction chamber by the particular solvent ifany is capable of occurring, and it also provides ample time forsecondary dissolving to take place, before a solvent is changed. Afterthe solvent is changed, the device provides sufiicient time for properdissolving to occur between the new solvent and the compounds in thefraction chamber I35, whereby the pen I64 will move to the rightwardside of the line I6'I. As shown in Figure 13, the instrument II) in thisembodiment is preselected to fill three containers after the curve I69has dropped below the mini" mum line I61. Thus, as long as .the curveI59 remains to the left of the line I67, the solvent being fed into thefractionating column I5 will be changed after three containers I2 arefilled The line;III1.(Eigurel3) made onthe tape. I66.

bycthepen. IE5. recordsl by the indices I'I2 points at which. thesolvent. being. fed. into. the. fractionating column; I5 .is changed.Asshown in Figure 20, two..or.more. solvents inlseparate receptacles III arenormally usedin carrying out.

anioperationof the instrument IIL.

MECHANICAL OPERATION The turntablel I is provided with a plurality ofcontainers I2, and. as many solvents as are required tocarryout aparticular operation are;

placed in receptacles I4I, mounted upon the platformv I42 and.connected, as by the outlet pipes: I45l:(Fig.ures 1. and 20), to themanifold chamber I 32: at the top of the fractionating column I5. Theinletpipe MA on; the: receptacle. IIII is connected toa pairoflregulatingvalves I5.I and I52. The electrical circuitry, hereinafterdescribed, of the instrument:I;.isturned on and the first solventwillcommence collecting. fractions dissolvable there.- into; A-gas underpressure is fedinto the re.- ceptacle: IIII; (Figure. 1) throughthe-supply pipe I55,.the:valve I52.and.the inlet pipe. lfiilithereby,

urging the solvent. in the receptacle to how. through the. manifold I32.This solventin. the manifoldchamber I32 passesdown. through the.connectioni pipei I35, into. the solvent control chamber" I 3.I.andthentdown through the fraction chamber. I39, in which certaincompounds are held; The. auxiliary pressure will continue to force thesolvent into the manifold. chamber I3i2runtillthe1floatvl33has beenraised to a level wherezthe stem. I34thereof extends between thefieldtwindings I36, I31 and. I38. The rod. I28 (Eiguretl2), actingvasv'a. core, induces a current flow. through. the solenoid F56 whichresults in.

energization of the solenoid whereby the valve I52lis closedandthe-valve I5I is opened. Since thepressureof. the gas in the pipes I45and I43 isneutraliz'ed by this change of valves, the solvent will stopflowing into the manifold I32. However, as soon as theiioat I33 dropsdown, the solenoid: I58 will be deenergized and the valvesJEI and IE2will be reversed, thereby permitting the gas passing through theauxiliary supplypipe! 55, which has a higher pressure than the gaspassing through the valve I 43, to urge the solvent out of thereceptacle MI.

The solvent in the manifold chamber I32, the connection pipe I35 and thesolvent control chamber I3I (Figures 1, 5, 12 and 14), will slowly passthrough the fractionating chamber I30 while taking into solution thosecompounds dis solvable therein. The solvent and solute will thenpassthrough the transfer tube 98 into the absorption cell 86 and thenceinto a container held in: the'turntable II directly under the outlet IIII inthe cell 86. pass through the absorption cell 86, the solutetherein will absorb portions of the radiation from the tube "I9: At thesame time, solvent passes fromthemanifold chamber I32- through thebypass tube lflflidirectly into the absorption cell 81' through whichthe radiation from the tube I9 also passes. Accordingly, the radiationstriking thephoto-electric tube I05 will be a function solely of theabsorption of the solvent, whereas the? radiation from thetubeI9:passing through the absorption. cell 86 and striking thephotoelectricltubew lfllluwillhbe a function of both the I45. from eachstopper.

As the solvent and solute shown by the dotted line IBI' in FigurelS, the

solvent being fed from a receptacle I II to the manifoldchamber I32will'remain the same. As each container I2 is filled to a predeterminedlevel with such solute and solvent, radiation from the lamp I15 will beintercepted by the liquid in the container I2 and diffracte-dtherebythrough the slot I24 onto the filament of the photo-tube I 22. By meansof switch circuitry, described hereinafter, the tube I22 will theninitiate energization of the solenoid 62 (Figures 1 and 4) whereby theclutch 45willengage the motor 31,. thereby causing the. turntable II torotate until the contact I3 of .the switch I2 engages a projection 23 onthe edge 22of the top disk II, whereupon the turntable is stoppedabruptlyby the braking function of the clutch 45.

The energization of the solenoid by the tube I22 is of onlysufficientduration, to effect such rotation of the turntable that the contact I3,will become disengaged from a projection 23, Where it will be wheneverthe turntable III is not rotating, Immediately thereafter, the switch I2takes over and continues the energization of the solenoid 62" until thecontact I3 again engages a projection 23. Upon deenergization of thesolenoid 62, the spring 63'causes the clutch member 50 to engage theclutch plate ll, whereby the rotation of the turntable II is immediatelyarrested.

Such rotation of the turntable will place the next adjacent containerinto position for filling. This sequence of operations continues as longas the absorption of radiation from the tube I9 by thefiuid passingthrough the absorption cell 86 remains above a predetermined orpreselected minimum.

As soon as the absorption drops below said predetermined minimum, thecounter IfiI (Figure zil) goesinto operation to automatically count apreselected-number of containers to be filled by the solvent and solute,even though the absorption is below said minimum, after which saidcounter then initiates a change in the solvent being fed into themanifold chamber I32. The counter ISI is automatically reset andcommences counting the preselected number of containers as they arefilled with the new solvent. andsuch solute as may be removed by the newsolvent from the fraction chamber I33. If the amount of solute, orcompounds dissolved by the next solvent do not absorb radiation from thelamp I9 above said" minimum before the preselected number of' containersis filled with this newsolvent,,as indicated in the central portion ofFigure 13, the counter I JI will initiate a change to a third solvent.After such changing of. solvents, the counter automatically resetsitself and commences to count containers containing the third solvent.However, if this particular solvent dissolves sufiicient compounds fromthe fractionating chamber I30 to absorb radiation from the tube I9 abovesaid minimum, the counter will then permit filling of containers I2 withthis solvent and solute indefinitely until,

As long as the absorption by such. solute remains above the minimumgraphically ELECTRICAL SYSTEM Although a large portion of the circuitsherein utilized are conventional, sufficient of them have beenparticularly adapted to the mechanical parts herein disclosed and forthe specific purposes herein contemplated, that it is deemed desirableto describe said circuits in detail in the interest of presenting acomplete disclosure. It should be understood, however, that these itemsof circuitry are herein described for illustrative purposes only andthey may in many instances be substituted or completely replaced byother conventional circuits, providing only that the particularfunctions and purposes herein described are preserved.

FILL CONTROL LAMP CIRCUIT The fill control lamp II may be of anyconventional type. it is preferred that said lamp have a pair offlaments, one of which is normally energized and the second of whichbecomes energized only upon the failure of the first. Figure illustratesa suitable circuit.

In this circuit (Figure 15) the source I energizes the primarytransformer windings 202 and 263 which in turn energize the secondarytransformer windings 2M and 255, respectively. The secondary windingsare connected in series with the main filament 206 of the fill controllamp H5 and with the variable resistor 2Ill. Thus, in normal operationthe filament 206 will be energized by current induced in saidsecondaries and passing through the filament and through the variableresistor During such normal operation the winding of the relay 258,which is connected in parallel with the variable resistance 253i, islikewise energized and holds the relay contacts 259 open against theaction of a spring 2I2 normally tending to close said contacts.

The auxiliary filament 2H1 of the lamp H5 is connected in series withthe secondary winding 2% and the contacts 209. The pilot lamp 2 isconnected at any convenient point in this circuit. Here it is inparallel with the auxiliary filament 2 I 8' and, therefore, also inseries with the contacts 259. Thus, when the main filament 206 burnsout, the circuit including the relay winding 2Il8 is broken and thecontacts 209 close. Accordingly, the secondary winding 204 energizes theauxiliary filament 2IIl and simultaneously energizes the pilot lamp 2,which warns the operator that the main filament 255 has burned out, thatthe machine is operating upon the auxiliary filament 2H] and that,therefore, the fill control lamp H5 should be replaced. By placing thepilot lamp 2H in parallel with the auxiliary filament ZII], the saidpilot lamp will be illuminated upon opening of the relay contacts 209regardless of whether or not the filament m is illuminated. Thus, awarning is provided even though the auxiliary filament 2H] has alsobecome damaged and fails to operate.

FILL CONTROL CIRCUIT The fill control circuit (Figure 16) operates uponthe energization of the photo-tube I22 by the fill control lamp I I5 andeffects initial movement of the turntable II each time a given containeris filled to a predetermined level. A portion of the circuit may bearranged to respond only to pulses from the photo-tube I22 having thefrequency provided by the light chopper I2'I However, for purposes ofsafety L,

(Figure 20) in order to insure that the turntable II will move only inresponse to light emanating from the lamp II5 and not to stray lightfrom the outside sources. Obviously, this portion of the circuit may beremoved where no light chopper is used, but it is here shown in theinterest of completeness. Further, this circuit is provided with timedelay means in order that the movement of the turntable will beinitiated only when the container is actually filled to the proper leveland will not be initiated by splashing or by drops of solution passingthrough the light beam.

Referring now to Figure 16, the photo-tube I22 is connected through ashielded cable 223 to the amplifier circuit indicated generally at 224,which circuit may be conventional. In this particular instance, however,the pulses from the phototube I22 flow through the load resistor 222 andthe resultant voltage differential is applied through the capacitor 225of the grid 2250f the amplifier tube 22I, which amplifier tube isconveniently of the 6AT type. The amplifier tube 22? is arranged tooperate on the lower portion of its characteristic curve so that itsoutput is sharply limited. That is, the A. C.-voltage at the anode 22Ithereof cannot rise above approximately one volt regardless of thevoltage on the grid 225. The output at the anode 22I of ampliiier 2.2Tis coupled through the capacitor 228 and the resistor 225 to the grid235 of the amplifier tube 23!, which amplifier is conveniently of theSAUG-type. Other suitable conductors connect the resistor 222 in aconventional manner through other resistors to the cathodes of therespective amplifier tubes 222i and 23 I, and to the shield grids of theamplifier 23L The output of the amplifier tube 23I is conductedto aparallel resonant circuit 239 composed or" the capacitors 24? and 2M andthe reluctance M2, which elements are arranged to tune said resonantcircuit 235 to the frequency of the light chopper I22? which, in thisinstance, is 540 cycles per second. Thus, unless the voltage applied tothe grid 225 of the amplifier 227 has a frequency of 540 cycles persecond, or some simple fraction thereof, very little voltage isdeveloped across the parallel resonant circuit 239.

The output of the amplifier tube 23I is also coupled through thecapacitor 2:35 to a suitable rectifier which in this instance isprovided by the diode plates 2M and 2&5 in the tube 221. The rectifiedvoltage is then filtered by the resistor 24% and the capacitor 25? andfed through resistor 2&8 to the grid of the thyratron 259.

The anode of the thyratron 2&9 is connected through the resistance 2% toone side of each of the three capacitors 25 I, 252, and 25s, the otherside of each of said three capacitors being connected to ground. Theside of said capacitor to which the resistance 25% is connected is alsoconnected in series with resistances 25d and 255, which are in turnconnected to the conductor 256. Said conductor 25% is connected throughthe resistance 25l to that side of the parallel resonant circuit 238opposite from that side to. which the anode of the amplifier 23I isconnected.

The thyratron 250 has its grid connected intermediate the resistances254 and 255, and its cathode is connected to the conductor 255. A relayZlii has one end of its winding connected to the anode of the thyratron255 and the other end of its winding connected through the secondarywinding of a transformer 252 to the cathode of the thyratron 255. Theprimary winding of said transformer 262 is energized from any convenientsource, such as the secondary winding 269 of the transformer 263. Saidtransformer 263 also energizes the heaters of the two thyratrons and ofthe two amplifier tubes in a conventional manner. The capacitor 264bridges the winding of the relay 26L The contacts 265 are controlled bythe winding of the relay 251 and, when closed, complete a circuitthrough the conductors 266 and 261 which are connected to the poles 416aand 4 I 1a of the connecting plug IA. A power plug 210 is connected tothe primary winding 21! of the transformer 263 and provides power forthe operation of this portion of the circuit. The micro-- switch 12 isconnected across the poles 54B and All of plug 2 in parallel with theturntable starting circuit 408 (Figure 18). The solenoid G2 is connectedto the poles M6 and 54! of plug 2.

If an empty container I2 is in the fill position, so that the photocelli222 is not energized, no voltage is applied to the grid of thethyratron 249. Thus, the thyratron 249 will conduct at a sumciently lowanode potential as to effect a substantially continuous conduction andthe capacitors 252 and 253 are thus kept continually dischargedtherethrough. Under these circumstances current flows through theresistance 255 from the source provided by the transformer 263. In fillposition, one of the cams 23 will hold the micro-switch 12 open so thatthe solenoid B2 is not energized until the turntable starting circuit Sagain provides a connection between terminals M5 and All of plug 2. Thevoltage drop across said resistance 255 is applied through theresistance 215 to the grid of the thyratron 260. This negative biasprevents the thyratron 260 from conducting in response to the potentialsupplied by the transformer 262 and thus the winding of relay 2B! isde-energized and the contacts 265 remain open. This, by reason ofsubsequent circuitry, results in the turntable l remaining motionless.

However, when the container in fill position is filled, the photo-tubebecomes energized, and a negative potential appears on the grid of thethyratron 249 and prevents it from conducting.

This first allows the capacitors 25!, 252 and 253 to charge in reponseto the potential provided by the source 253. However, as thesecapacitors become charged, the voltage drop across the resistor 255becomes so small that the negative bias on the grid of the thyratron 265is diminished sufficiently to permit said thyratron 269 to conduct. Thecapacitors 25L 252 and 253 provide sufficient delay between energizationof the photo-tube I22 and conduction of the thyratron 269 that theturntable starting circuit 456 will respond only to a filled containerand not to splashing or to drops of solution falling from thefractionating column 55. Conduction by thyratron 2% energizes the relay26! thereby closing the contacts 265 thereof. The capacitor 264 isprovided to prevent the relay 26! from. chattering.

Closure of the contacts 255 operates through subsequent circuitry toefiect movement of the turntable l I in a manner described in detailelsewhere herein.

COMPARATOR CIRCUIT The comparator circuit (Figure 17), which isessentially responsive to the differential in output between the twophoto-tubes I84 and H15, opens or closes a relay whereby a connection ismade which actuates a portion of the herein aiter described counting andcontrol circuit. Said differential in photo-tube output varies accordingto the concentration of a selected solute in a given solvent flowing ata given time from the fractionating column l5, as described hereinabove.The comparator circuit also provides a small output potential which isconnected to the recorder I (it (Figure 20) for recording the operationof the comparator circuit.

The comparator circuit includes a pair of amplifier circuits [H8 and Eli, one connected to each of the photo-tubes iii-i and m5, whichphototubes may be of any conventional t, pe capable of producing anelectrical response corresponding to change in light intensity fallingthereon. Each of said photo-tubes is connected through its respectiveamplifier circuit to said comparator circuit, which latter opens andcloses a control relay.

Now considering the comparator circuit (Figure 1?) in more detail, thepower source 58!} is connected through the conductors till, the resistor695, the conductor 68! and the resistor till to the junction 683. Thevoltage regulator tube 882 and said resistors 69!! and 69! assure aconstant voltage being maintained at said junction point. From saidjunction point 683, one portion of the current travels through theresistor 6G2 to ground. The capacitor 663 bridges said resistor andfunctions to isolate two photo-tube circuits. Another portion of saidcurrent travels through resistor Gill and the shielded cable 568 to andthrough the photo-electric tube M5 to ground. The final portion travelsthrough the resistor 605 and the shielded cable GM to and through thephoto-electric tube Hi l to ground. Variations in light falling upon thephoto-electric tubes will vary their respective conductivitycharacteristics and hence vary the potentials at the junction points 685and 686. Conductors 697 and t le connect said junction points 685 and6%, respectively, through the capacitors 608 and 595 to the controlgrids of the amplifier tubes 5% and 599, also respectively. Saidamplifier tubes are each the first of the series of such tubes in theamplifier circuits 6!! and EH], respectively, which circuits areconventional and are hence indicated only schematically. i

The anode output from the tubes 599a and .2931; in each of saidamplifier circuits 6H] and 6i i, respectively, is conducted by theconductors 512 and 613, respectively, to the primary windings of a pairof transformers 6M and (H5. One end of each of the secondary windings ofsaid transformer GM is connected through the. conductor 6!! and a highresistance 618, of the order of thousand ohms, to ground through theconductors BIB, 629, 62! and 522. The cathode of the rectifier 616 isalso connected to ground. conveniently through the conductor 622. Acapacitor 623 may also advantageously be provided to smooth fluctuationsin the output of the rectifier SIB. The tap 524 is adjustable withrespect to the resistor 6 l 8 and connects same through the conductor625 to the cathode of the thyratron 526, The anode of the thyratron 628is connected through the protective resistance 62? to one end of thewinding of the relay 628, to which the capacitor 629 is connected inparallel, and the other end of said winding is connected to one end ofthe secondary winding of the transformer $38. The primary winding of thetransformer 93?! is connected to a 6.3 volt power source described inmore detail elsewhere herein. The other end of the secondary winding ofthe transformer 689 is connected to the cathode of said thyratron 625.

The grid of the thyratron 626 is connected through a resistor 63l to oneside of the small, biasing battery 632 which battery provides on theorder of 1.5 volts. The other side of said battery 632 is connectedthrough the conductor 633 to a point between a pair of relatively largeresistors B34 and 835, which in a preferred embodiment of this inventionare of the order of 56 thousand ohms. The other end of the resistor 634is connected through the conductor 63% and E54, and through a smaller,such as a thousand ohm, resistor 631 to the junction point 938. Theother end of the resistor 635 is also connected to the junction point638, which junction point is then connected through the conductors 639,i350 and 644 to the end 640 of the secondary winding of the transformerM5. The contacts 64! and 642 of the relay 643 are connected,respectively, to the conductor 636 and to the junction point 638. Thearmature 645 of the relay 643 is connected through conductor 6% to theconductor 633.

Referring again to the transformer 515, the end 640 of its secondarywinding is connected through the conductor 644 and 660 and the capacitor661 to ground through the conductors 662, 62! and 622. The conductor S54is also connected to ground through a high resistance 663, such as 100thousand ohms.

The winding of the relay 643 has a capacitor 641 connected in paralleltherewith and a resistor 648 in series with said winding and capacitor 62?. The conductor between said resistor i348 and said capacitor 641 isconnected to a 150 volts D. C. source, and the conductor between saidwinding and the capacitor 641 is connected by the conductor 6A9 to thecontact 65d of the relay 623. The armature 65! of the relay 628 isconnected through the resistance 652 to ground, thereby to complete thecircuit for the winding of the relay 643. The capacitor 653 and theresistor 65? are provided to prevent arcing of the contacts 65! and 650.

The contact 664 of the relay 643 is connected on its respective twosides to the contacts 565 and 666, which co-act with the contacts 430and 433 appearing on plug 3 in Figure 18. The contact 664 opens andcloses the circuit between the connections 430 and MM. which function tooperate the circuitry shown in Figure 18 and described in more detailhereinafter.

With the photo-tube 1M exposed to radiation from the lamp 19 passingthrough the solvent only, the output of the transformer EH5 iscomparatively steady. This output passes through the thyratron 626, whensaid thyratron is conducting, and energizes the winding of the relay 628by which to hold the contact 650 closed. This energizes the winding ofthe relay 643 and holds the contact 654 closed, as well as holding thearmature 645 against the contacts 64L Since only solvent passes throughthe cell 81, no radiation passing therethrough from lamp 19 will beabsorbed thereby before falling upon photo-tube Hi5. Thus, the output oftransformer 614 will be comparatively constant.

Assuming now that the solution discharged from the fractionating column[5 has insufiicient solute dissolved therein to absorb radiation fromthe lamps 19, said radiation will fall upon the photo-tube Hit and theoutput voltage of the transformer 665 will equal the output voltage ofthe transformer M4. The adjustability of the point of contact betweenthe conductor 624 and the resistor 618 provides the means forcalibrating the system correctly'to this balanced condition. With therelay 628 actuated and the contact etc closed, the relay 643 is actuatedand the armature 645 is connected to the contacts 6M. Since current fromthe secondary winding of the transformer 6H5 passes through theconductors 644, 660 and 639, the resistance 63! and resistance 663 toground, when the relay 643 is positioned as shown in Figure 17, apotential is taken from the junction point 638 through the contacts 642,the conductor 646 and the conductor $33 to the control grid of thethyratron 626. In the energized position of the relay 663 a potential istaken from the junction point Sit in the conductor 654 and carriedthrough the contact 6M and the conductors 646 and 633 to the grid ofsaid thyraton 626.

Thus, when there is no absorption of radiation from lamp 79 by thesolution discharged from the fractionating column there will be apotential applied to the conductor 644 of the same value as thatsupplied to the conductor 6H. This is conducted, as above described, tothe grid of the thyratron 626 and, together with the biasing potentialof the battery B32, acts to block the thyratron. So long as thethyratron is blocked, the relay 628 remains open as shown and the relay653, as appearing in Figure 17, is not energized. Thus, the connectionsbetween the terminals i565 and 666 is open at the contacts 664 of relay643.

However, as absorption of radiation from lamp '59 increases, the outputof the photo-tube 1M decreases, and the potential on the control grid ofthe thyratron 626 will also decrease. When this grid potential decreasessufficiently to'permit the thyratron to fire, the relay 628 becomesenergized and through the closing of the contact {$59 the relay 643 isalso energized. This closes the contact 664 and provides a connectionbetween the terminals G65 and 666. Simultaneously this connects thearmature 645 to the contact 5M and thereby connects the grid of saidthyratron 626 to the conductor 644 through the resistor 631, instead ofdirectly as before. Thus, since the potential in this instance appliedto the grid of said thyratron 626 is taken after the occurrence of thedrop through the resistance 631, this grid potential of said thyratronimmediately becomes still more negative. Accordingly, in order to causethe thyratron again to conduct, the potential in the conductor 644 mustbecome somewhat more positive than would have been necessary had adirect connection between said grid and said junction point 6588 beenmaintained. The purpose of this is to insure that the concentration ofsolute in the product of the fractionating column has actually changed amaterial amount before the system is caused to respond thereto, and toprevent response of the system to the minor changes in saidconcentration which are always present and which, if not damped out,cause a chattering of the entire equipment whenever they occur near thecritical point. It will, of course, be understood that the balancing assuch, of the outputs of the two photo-tubes Hi l and W5 occurs merely bybalancing of the grid and cathode of the thyratron B26 and effecting theopening and closing of the contact 66% according to whether or not saidthyratron conducts.

The power supply for the foregoing equipment is of any conventiona1 sortby which a rectified and reasonably smooth direct current is supplied bythe rectifier 680 to the conductor 61'! from the alternating source 672and by which a small volt-

1. THE METHOD OF CARRYING OUT A CHROMATOGRAPHIC FRACTIONATING OPERATIONEMPLOYING A SERIES OF SOLVENTS IN CONJUNCTION WITH A COLUMN, COMPRISINGTHE STEPS: WITHDRAWING SOLUTION FROM A FRACTIONATING COLUMN; PASSINGTHROUGH SAID SOLUTION OF BEAM OF RADIANT ENERGY OF A CHARACTER CAPABLEOF BEING PHYSICALLY AFFECTED BY A SELECTED